The NYTimes says, "The [IMF] told its staff and its board of directors about the attack on Wednesday," but they didn't go into detail about the hack.

However senior people familiar with the attack tell the NYTimes that it was a "very major breach."

The fund is fully functional, but according to the Times:

The concern about the attack was so significant that the World Bank, an international agency focused on economic development, whose headquarters is across the street from the I.M.F. in downtown Washington, cut the computer link that allows the two institutions to share information.